Patent GB-415698-A (GB)
Title: Improvements in or relating to the electrical propulsion of ships
IPC: B63H23/24
Filed: 1932-11-21
Abstract: 415,698. Systems for transmitting mechanical power. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London, GARRARD, C. C., and COATES, H. J., c/o General Electric Co., Witton, Birmingham. Nov. 21, 1932, No. 29447. [Class 38 (iv).] In an electric ship propulsion system provided with a number of generators such as alternators 9, 10 and a number of motors 7, 8 associated, each with a generator, and driving propellers, any generator may drive its motor alone or with other motors in parallel but the generators cannot be paralleled, moreover, the generators are connected to motors through series connected switches such as 3, 4 arranged in different cubicles and interlocks are provided for preventing access to any switch cubicle until all the switches therein are open and the series connected switches, 3 and 4, are open so that all the connections in the cubicle are dead. The arrangement is such that one part of the plant, such as generator 9 and motor 7 may be operated whilst the rest of the plant is being inspected or repaired. Each generator is provided with a master controller 19, 20 which controls the supply of excitation to the corresponding motor fields 17, 38 through contactors 25, 35 and switches 13, 16, and to the corresponding generator fields 32, 43 through contactors 27, 40 and switches 14, 17, whilst reversing switches 5, 6 are also controlled from the corresponding controllers. The excitation switches 13, 14 and 16, 17 are coupled to isolators 1 and 2 respectively for each generator and tie switches 3, 4 are provided coupled to switches 15 and 18 for connecting the two motors and their fields in parallel so that they may be supplied from a single generator 9 or 10 under the control of a single field controller 19 or 20. The switches 1, 13, 14 operated from a common shaft are under the control of a handwheel through gearing and are enclosed in a cubicle 11 with switches 3, 15 also operated from a common shaft and controlled by another hand-wheel. Switches 2, 17, 16 and 4, 18 are similarly arranged and controlled in another cubicle 12, the isolator switches 2 being operated from a shaft 54 through gearing 53 and a hand wheel 51 and the tie switches 4 from a shaft 55 through gearing 56 and a hand wheel 58. Notched interlock disc wheels 60, 59 are provided on the shafts 57, 52 of the hand wheels 58, 51 and engage interlock wheels 66, 61 mounted on shafts 67, 62 and controlled by levers 68, 63 which are interconnected by a link 64 which is controlled by an interlock lever 50 through a shaft 49 and linkwork 65. The interlock lever 50 is mounted on the master control cubicle 20 and its shaft 49 is provided with an interlock disc 48 which co-operates with a disc 47 on the shaft 46 of the handwheel 22. The arrangement is such that, with the lever 50 in the upper position the hand wheels 51, 58 cannot be moved and are therefore locked in the " on " or " off " positions, but the master controller 22 can be rotated, with the lever 50 in the lower position into which it can only be moved when the master controller 22 is in the " off position, the master controller is locked in the off " position, and the handwheels 51, 58 are free to be moved. This ensures that the isolator and tie switches 2 and 4 can only be operated when the master controller 22 is in the " off '' position. A similar arrangement of interlocks is provided on the cubicle 11 and the master controller 19, 21 through linkwork 83, Fig. 3, and interlock discs 86, 90 (not shown), and 87, 91 (not shown). The links 83, 64 also control the interlock discs 60, 91 respectively operating on the other tie switch hand-wheel such as 58, since the shafts 85, 67 of their interlock discs 87, 66 carry also interlock discs 88 and 89 operating on the discs 60, 91 respectively not shown in Fig. 3. The hand-wheels such as 58, 51 are provided with additional interlock discs 73, 69 on their shafts 57, 52 and corresponding discs 76, 78 on shafts 75, 77 on the other cubicle. These discs co-operate with interlock discs 72, 70 and 79, 80 connected together by shafts 71 and 81 which are connected by a link 82 and operated from a common handle 74. The handle 74 has three positions and the arrangement is such that, assuming that the master interlock levers 50 are in positions favourable for the operation of the hand-wheels on the cubicles, the lever 74 and its interlocks on the hand-wheels allows only three combinations in the operation of the hand-wheels, (a) Closure of both tie switches and of one selected isolator switch, (b) Closure of both tie switches and of the other isolator switch, (c) Closure of both isolator switches only. This arrangement permits paralleling of both motors on to one or other of the generators, or separate operation of each motor from its generator but prevents paralleling of the generators. The interlock levers, such as, 50 associated with the master controllers, when moved down release keys for opening the respective cubicles by trapped key methods so that access can only be had to the cubicles when they are dead, although one or other cubicle may be in operation. Three keys are provided all of which must be used before either cubicle can be opened, one key being only obtainable when the corresponding master controller 21 or 22 is in the " off " position, another when the corresponding isolator is open and a third when the tie-switch operating gear is in the " open " position. The general control is such that when a master controller is turned to its first position the turbine driving the corresponding generator is run up to <1>/30th full speed the associated reversers being locked inoperative. In the next position the turbine is speeded up to <1> /5th full speed, the generator is doubly excited, and any motor associated with the controller is run up as an induction motor to <1>/5th full speed, further movement of the controller being prevented until this speed is reached. In the third position, the motor is excited and pulls into synchronism, and in the fourth position the generator excitation is reduced to normal, an automatic variable speed turbine governor not becoming operative so that further movement of the controller operates thereon so as to give speeds between <1> /5th full speed and full speed. During the return movement the field circuits are retained until the controller is in the first position. Below <1>/5th full speed the control is independent of the governor. The invention may be applied to other types of systems including D.C. and Ward-Leonard types of control.